How to create time based queue with priority in Python?

Question

I need to create jobs queue with certain time frame and priority, like

name      time                              priority
-----------------------------------------------------
Job 1:    from 13:00 till 14:00 5.5.2018    10
Job 2:    from 14:00 till 15:00 5.5.2018    10
Job 3:    from 14:00 till 15:00 5.5.2018    1

Now what I need is to allow Job 3 to override Job 2 because it has greater priority and to take its place. I managed to create job queue with priority using this https://pymotw.com/2/Queue/

But I need to have time frames. The program must give me info that Job 2 is delayed or canceled, in case Job 3 takes its place.

The execution result should be

Job 1 (because it has closest time)
Job 3 (because it has higher priority than Job 2)
Job 2 (would not execute, because Job 3 took its place)

fferri · Accepted Answer · 2018-05-05 11:08:19Z

1

Just ensure that the items you push in your priority queue can order naturally according to your criteria (e.g.: first datetime, then priority).

Inserting tuples in the form (datetime, priority, jobname) would do the job:

import heapq
import dateutil
import dateutil.parser
h = []

# push items into queue:
heapq.heappush(h, (dateutil.parser.parse('13:00-14:00 5.5.2018'), 10, 'Job 1'))
heapq.heappush(h, (dateutil.parser.parse('14:00-15:00 5.5.2018'), 10, 'Job 2'))
heapq.heappush(h, (dateutil.parser.parse('14:00-15:00 5.5.2018'), 1, 'Job 3'))

# extract items from queue:
print(heapq.heappop(h))
# (datetime.datetime(2018, 5, 5, 13, 0, tzinfo=tzoffset(None, -50400)), 10, 'Job 1')
print(heapq.heappop(h))
# (datetime.datetime(2018, 5, 5, 14, 0, tzinfo=tzoffset(None, -54000)), 1, 'Job 3')
print(heapq.heappop(h))
# (datetime.datetime(2018, 5, 5, 14, 0, tzinfo=tzoffset(None, -54000)), 10, 'Job 2')

edited May 5, 2018 at 11:08

answered May 5, 2018 at 10:41

fferri

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8 Comments

emir Over a year ago

I get the error NameError: name 'datetime' is not defined. Also I need the timeframe, from - to. OK, maybe I could use starting time and duration.

fferri Over a year ago

@emir: where'd you get that datetime from? Not from my code I suppose.

emir Over a year ago

Now it is commented, and there is no error now, but when I run it nothing happens.

fferri Over a year ago

@emir: the dateutil.parser would pick the start date. If you have a different criteria for establishing the priority of such datetime range, you need to transform it to some orderable data type.

fferri Over a year ago

@emir: try to print(heapq.heappop(...)) each of the last 3 lines

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